The prior art teaches the utilization of various chemical formulations to remove residues and clean wafers, following a resist ashing step. Some of these prior art chemical formulations include alkylene compositions containing amines and/or tetraalkyl ammonium hydroxides, water and/or other solvents, and chelating agents. Other formulations are based on acidic to neutral solutions containing ammonium fluoride.
The various prior art formulations have drawbacks that include unwanted removal of metal or insulator layers, and the corrosion of desirable metal layers, particularly copper or copper alloy features. Some prior art formulations employ corrosion inhibiting additives to prevent undesirable copper metal corrosion during the cleaning process. However, conventional corrosion-inhibiting additives typically have detrimental effects on the cleaning process because such additives interact with the residue and inhibit dissolution of such residue into the cleaning fluid. Furthermore, conventional additives do not easily rinse off the copper surface after completion of the cleaning process. Such additives, therefore, remain on the surface sought to be cleaned, and result in contamination of the integrated circuits. Contamination of the integrated circuit can adversely increase the electrical resistance of contaminated areas, and cause unpredictable conducting failure within the circuit.
The formulation of post chemical mechanical planarization (CMP) cleaners for advanced integrated circuit manufacturing, such as copper and tungsten interconnect materials, includes slurry removal and residue dissolution components that accelerate the physical cleaning process. However, these conventional additives typically have detrimental effects on the metal surface by increasing resistance and corrosion sensitivity.